It has been shown that Li ion causes the decrease in brain glucose-1,6-P2 and decreases the fraction of glucose-bis-P synthase that is in the active Zn2 ion-form from 65 to approximately 20% of the total enzyme. We wish to examine these effects on localized areas of the brain to obtain correlates with rates of glucose utilization as measured by the deoxyglucose method of Sokoloff and with the distribution of Zn2 ion in different areas. In addition we will purify and study brain glucose-1,6-P2 phosphatase which must be important in determining the steady state level of this important regulatory substance.